We are continuing our work on the composition and assembly of Vesicular Stomatitis Virus (VSV) envelope proteins and are now also studying the interaction of these proteins with the virion ribonucleoprotein (RNP) core which contains the VSV RNA dependent RNA polymerase. We are also examining the mechanism by which newly replicated virus RNA molecules assemble with the RNP proteins. We have isolated and characterized VSV replicating RNP complexes from infected cells and have studied regulation of plus and minus strand synthesis early and late in the infection. We are now trying to establish an in vitro replication system to further study this aspect of VSV infection.